Mining apparatus



Nov. 4, 1941. .J. F. JOY 2,261,162

MINING APPARATUS A Filed Feb. 28, 1938 l0 Sheets-Sheet l r 0, am@ v. mwmw www. u MQ ww bw w S ww w WM f @l 6 .n w N NQN h w ww w mw Nov. 4, 1941. J; F. JOY

MINJNG APPARATUS 1o sheets-shea 2 Filed Feb. 28, 1938 Y a@ f Nov. 4, 1941.

J. F. Jo'Y MINING APPARATUS Filed Feb. 28, 1958 .1o sheets-sheet 5 Nov. 4, 1941. J. FQ JoY MINING APPARATUS Filed Feb. 2a, 1958 1o sheets-sheet 4 O O O w Y o 1o shets-sheet 5' Nov. 4, r1941. J. F. JOY

MINING APPARATUS Filed Feb. 28; 1938 Nov. l4, 1941. J. F. JOY

` MINING APPARATUS Filed Feb. 28, 1938 llll gc A;

Nov. 4, 1941. F JOY 2,261,162

f MINING APPARATUS l' Fild Feb. 28,A 1938v I lO Sheets-Sheet 7 F" Y 2 f 4;

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Il L v 1 I 1 d d w y :g5 I Wg 1m/MMI@ Nov. 4, 1941. J. F. JOY

MINING APPARATUS lO Sheets-Sheet 8 Fi-led Feb. 28, 1938 J. F. JOY

MINING APPARATUS Nov. 4, .1941.

l0 Sheets-Sheet 9 Filed Feb. 28, 1938 E Jas/e Nov. 4, 1941. J, F, JOY 2,261,162

MINING 'APPARATUS Filed Feb. 28, 1958 10 Sheets-Shetvl liana/gon v ESB/MIKE@ dfi@ Patented Nov. 4, 1941 MINING APPARATUS Joseph F. Joy, Claremont,

N. H., assignor to Sullivan Machinery Company, a corporation of Massachusetts Application February 28, 1938, Serial No. 192,918 24 Claims. (Cl. 2622-28) This invention relates to mining apparatus, and more particularly to improvements in a coal mining apparatus of the combined cutting and loading type for cutting the solid coal, breaking down the cut coal from the solid and loading the broken down coal.

An object of this invention is to provide an improved coal mining apparatus for completely removing the solid coal from its natural bed in a coal seam, wholly without the use of explosives or other blasting means, and for loading the coal as it is removed from the coal seam. Another object is to provide an improved coal mining apparatus of the combined cutting and loading type having improved means for cutting and breaking down the coal. A further object is to provide in an apparatus of the above character, improved kerf cutting means for cutting superimposed kerfs in a coal seam to form a core of coal between the kerfs, and for breaking down sections of the core as cutting progresses. A still further object is to provide an improved kerf cutting means comprising a pair of superimposed kerf cutters mounted for independent swinging movement and having associated therewith improved means for adjusting the top cutter in a vertical direction relative to the bottom cutter. Still another object is to provide improved means for tilting the top cutter ina plurality of directions with respect to the bottom cutter to effect breaking down of the-coal previously cut by the cutters. Another object is to provide an improved pivotal mounting structure for the kerf cutters comprising swingable arms on which the kerf cutters are pivotally mounted whereby flexibility in adjustment and a relatively wide cutting range may be obtained. Still another object is to provide an improved kerf cutting mechanism comprising superimposed kerf cutters, the lower kerf cutter being arranged in advance of the top keri cutter so that the bottom kerf cutter cuts in'advance of thetop kerf cutter, and embodying means for tilting the top kerf cutter relative to the bottom kerf cutter for effecting breaking down of the cut coal as vcutting progresses. A further object is to provide a cutting and loading apparatus oi the reversible type adapted to operate in either of opposite directions and having an improved reversible mounting structure forv the keri cutters so that the bottom kerf cutter may cut in advance of the top kerf cutter during either direction of cutting. Yet another object is to provide an improved cutting and loading apparatus having novel combinations and arrangements oi parts. Theseand other objects and advantages of the invention will, however, hereinafter more fully appear.

' In the accompanying drawings there are shown for purposes of illustration one form and a modification which the invention may assume in practice. i

In these drawingss Fig. 1 is a top plan view of a cutting and load-` ing apparatus constructed in accordance with an illustrative embodiment of the invention.

Fig. 2 is a side elevational view of thecutting and loading apparatus shown in Fig. 1.-

Fig. 3 is an enlarged central longitudinally extending vertical sectional view taken substantially on line 3-3 of Fig. 1, with parts shown in elevation.

Fig. 4 is anv enlarged cross sectional view taken substantially on line 4--4 of Fig. 1.

taken substantially on line lI--ll Fig. 5 is an enlarged horizontal sectional view taken substantially on line 5--5 oi Fig. 2, with partsY broken away ,tol show structural details.

Fig. 6 isa detail plan view of the bottom kerf cutterA showing the associated `means for retaining the broken down coal in the path of thek cutter chain. y Y vv.

Fig. 7 is a cross sectional view taken substantially on line 'l-l of Fig..-5. Y Y y Fig. 8 is a view in longitudinal vertical section taken substantially on line 8-8 of Fig. 5.

Fig. 9 is an enlarged cross sectional view taken on line 9-9 of Fig. 6.

Fig. 10 is a detail horizontal sectional view` takenon line lll- Ill of Fig. 9.

Fig. 11 is an enlarged cross sectional View of Fig, 2.

Fig. 12 is an enlarged horizontal sectional view taken substantially on line |2I2 of Fig. 2.

Fig. 13 is an enlarged cross sectional view taken substantially on line I3-l3 of Fig. 2'.

Fig. 14 is a horizontal sectional view taken substantially on line Ill- I4 of Fig. 11,

Fig. 15 is a diagrammatic view of the hydraulic iiuid system and the associated control means.

Fig. 16 is a horizontal sectional view through the valve box.

Fig., 17 isaV longitudinallyv extending vertical sectional view taken on line l'l--Il of Fig. 16.

Fig. 18 is a cross sectional view taken on line |8-l8 of Fig. 16. Y .Y

Fig. 19 is a top plan vie of la cutting and loading apparatus similar to that shown in Fig. 1, illustrating a modied form of supporting structure for the ker cutters.

Fig. 20 is a side elevational view of the cutting and loading apparatus shown in Fig. 19.

Fig. 21 is an enlarged central, longitudinally extending, vertical sectional view taken on line 2|-2I of Fig. 19, showing the pivotal mounting structure for the top kerf cutter.

Fig. 22 is a diagrammatic top view showing the cutting and loading apparatus in cutting and loading position at the working face.

Fig. 23 is a diagrammatic side elevational View.

Fig. 24 is a diagrammatic view similar to Fig. 23 showing the top kerf cutter in its tilted coal breaking position.

Fig. 25 is a diagrammatic end view showing the kerf cutters in cutting and breaking-down position.

In this illustrative embodiment of the invention, there is shown a coal mining apparatus of the combined cutting and loading, oor type mounted for sliding movement on its own bottom over the mine floor, although it will be understood that the apparatus, if desired, may be mounted on a wheeled truck for movement along a trackway, or tractor tread mounted. The cutting and loading apparatus generally comprises cutting and breaking down mechanism which operates to cut the solid coal, break down the cut coal from the solid and move the brokendown coal toward the receiving end of a conveying means associated with the cutting and breaking-down means; and the conveying means receives the broken-down coal and moves the same away from the coal face as cutting progresses, toward an elevated discharge position at the rear end of the apparatus.

In this illustrative embodiment of the invention, the reference character I designates the cutting and breaking-down mechanism, and 2 the associated conveying means. 'Ihe apparatus, in certain respects, is similar to that disclosed in my copending application Ser. No. 143,809, filed May 20, 1937, now matured into Patent No. 2,210,919, granted Aug. 13, 1940, and comprises a bottom skid plate 3 adapted to rest upon and slide over the mine floor, and this skid plate has extending lengthwise thereof parallel guides 4, 4 providing longitudinal guideways in which are slidably guided lateral guides 5, 5 formed integral with the lower plate of a sliding main frame 6 of the apparatus. Mounted on the forward portion of the sliding main frame 6 is a support l for a bottom kerf cutter 8 and a relatively adjustable support 9 for a top kerf cutter I0, the kerf cutters arranged in superimposed relation and mounted for independent swinging movement relative to their respective supports, in a manner to be later described.

As is described in the above mentioned copending application, the conveyor means 2 is mounted upon the main frame 6 of the apparatus and is herein of a well-known type comprising two parallel troughs l2 positioned in substantially the same transverse planes at the opposite sides of the main frame and secured to the latter, and each having an upright outer side wall i3. Arranged at the inner side of each of these troughs is a channel member i4 secured to the adjacent side of the main frame and providing a guideway l5 for the endless drive chain I6 of the conveyor. This drive chain comprises a series of two-part chain blocks l (Figs. 4 and 11) connected together by jointed strap links I8 (Fig. 1), and the chain blocks have formed thereon conveyor flights i9 adapted to engage the material in the troughs at one side of the conveyor and move ittherealong, as will hereinafter appear. The chain links and straps are connected together by suitable pairs of horizontal and vertical pintles to render the chain flexible in both horizontal and vertical planes, thereby to permit the chain to follow the contour of the conveyor guideways. It is to be understood, however, that any other type of chain which is adapted to flex in horizontal and vertical planes may be substituted for the one above described, without departure from the spirit of the invention. The flights may be of any preferred form adapted :to move the material to be loaded along the trough of the conveyor. Preferably, I have formed these flights integral with the chain blocks I1. The conveyor troughs l2 arranged at the opposite sides of the main frame 5 each comprise la horizontal rearward portion 2i! and a horizontal bottom front portion 2l, these front and rear horizontal portions being connected together by an inclined portion 22, and the forward portion 2l of the conveyor troughs being arranged near the floor level at the forward end of the main frame so that the receiving portion of the conveyor passes around the forward end of the mainframe near the floor level to receive the broken-down coal moved rearwardly away from the coal face by the bottom kerf cutter 8 and for moving the coal along one conveyor trough at one side of the main frame to elevate the coal to a suitable point of discharge at the rear end of the apparatus.

The driving means for the conveyor, as is also disclosed in the copending application above referred to, comprises a motor 23 (see Fig. 11) having a spur gear 24 keyed to its power shaft, this gear meshing, as shown in Fig. 14, with a spur gear 25 keyed to a shaft 26 suitably journaled within the main frame 6. Formed integral with and driven by the shaft 26 is a spur gear 21 meshing with a spur gear 28 keyed to a horizontal shaft 29. The shaft 29 is likewise suitably journaled within the main frame and has formed integral therewith a bevel gear 30 meshing with a bevel gear 3| having its hollow hub formed integral with a vertical shaft 32 suitably journaled within the main frame. J ournaled within bearings supported within the hollow hub of the bevel gear 3l is the lower end of a vertical shaft 33, this shaft being journaled at its upper end within a bearing supported within the upper portion of the main frame. Keyed to and driven by this shaft is a chain sprocket 34 connected by an endless drive chain 35 (see Fig. l) with a sprocket 36 which engages and drives the endless drive chain i6 of the conveyor. The hub of the bevel gear 3| is connectible by a sliding clutch 31 to theshaft 33. This sliding clutch comprises a sliding clutch member having clutch teeth engageable with clutch teeth formed on the gear hub and provided with usual operating means.

As is also described in the above mentioned copending application, means is provided for moving the apparatus bodily over the mine floor during maneuvering of the apparatus with respect to the coal face comprising a horizontal cable winding drum 38 journaled on a vertical shaft 39 and having formed integral with its upper flange a spur gear 40 adapted to mesh with and to be driven by a spur gear 4| formed on the lower end of the shaft 32. The drum shaft 39 is formed with an eccentric portion 42 suitably journaled within the main frame and having a rotating handle 43 for rotating the eccentric portion to move the drum shaft 39 in an arcuate path, thereby to move the drum gear ders46, 46 to effect-rectilinear feed of the bot- 40, as desired, into and out of meshing engagement with the driving gear 4l. 'Ihe handle 43 is pivoted to swing in' a vertical direction, and when depressed is engageable with stop lugs 44 for locking the drum gear in either of itsI adjusted positions. Wound on the drum is a feed cable 45 which may be`extended Vfrom the drum into connection'with a suitable anchor jack, so that as the drum is rotated to wind in the cable, the apparatus moves bodily over the mine floor, in an obvious manner.

Means is provided, as is also clearly described in the copending application above referred to, for moving the apparatus with a walking action over the mine floor and for feeding the main frame 6, together with the cutting and breakingdown means supported thereby, rectilinearly back and forth relative to the bottom skid. The

feeding means for effecting rectilinear feed is arranged longitudinally beneath the main frame in adjacency to the bottom skid and comprises a pair of reciprocable hydraulic cylinders `46, 46 arranged in parallel relation and pivotally connected at 41 at their front ends on horizontal axes todepending lugs integral with the main frame 6, and these cylinders contain pistons 48 having their piston rods49 extending rearwardly through the packed rear heads of the cylinders and pivotally connected at their rear ends on horizontal axes at 50 toA an upstanding bracket l secured to the rearward portion of the bottom skid 3. When fluid under pressure is supplied to one .end or the other of the cylinders 46, 46, the

4main frame 6, together with the cutting and breaking-down means supported thereby, may be slid either back or forth alongthe guideways on the bottom skid. To insure proper guiding of the main frame 6 during its rectilinear movement along the guideways on the bottom skid 3, the

' bottom of the main frame is formed with a centrally located longitudinal guiding slot 52 with whichV engages an upstanding guide block 53 formed integral with the bottom skid, as shown in Fig. 3. For effecting the walking action there are provided walking jacks, herein three in number, which are designated 54, 55 and 56, two located at the rear end of the main frame 6 at the opposite sides thereof (see Fig. 13) and one centrally located at the front end of the main frame (see Fig. 3). The centrally located front jack 54 comprises a vertical cylinder 51 having its piston rod 58 extending downwardly through the packed lower head of the cylinder, and this piston rod has a bottom abutment surface engageable with the mine floor. 'Ihe bottom skid 3 is centrally slotted at 59 at its forward end to permit movement of the jack within the slot when the main frame 6 is in its rearmost position on the skid 3. The rearwardly located side jacks 55 and 56 comprise, as shown most clearly in Fig. 13, vertical cylinders 6l] containing reciprocable pistons 6l having piston rods 62 eX- tending downwardly through the lower packed cylinder heads and having bottom abutment surfaces engageable with the mine floor. When fluid under pressure is supplied concurrently to the upper ends of the cylinders 51 and 60 the pistons are moved downwardly until the abutment surfaces on the piston rods thereof engage the mine floor, and then the cylinders are moved upwardly relative to the then stationary pistons to raise the main frame to relieve the skid of av substantial portion of the weight of the apparatus.l When the main frame is so raised, fluid under pressure may be supplied to the feed cylintom' skid 3 relative to the mainframe 6, and

thereafter the jack cylinders may be lowered and the pistons thereafter raised to bring the weight of the main frame back onto the bottom skid. Whenthe jack pistons are removed from their engagement with the `mine floor, fluid under pressure may be supplied to the feed cylinders 46, 4 6 toeffect forward rectilinear movement of the mainframe relative to the bottom skid. It will thus be seen that by operating the feed and jack cylinders the apparatus may be moved over the mine iioor with a walking action by successively feeding the main frame relative to the skid, relieving the skid of the Weight of the main frame, feeding the unweighted skid relative to the main frame and thereafter lowering the main frame back onto thev skid. 'Ihe means for supplying hydraulic pressure to the feed and jack cylinders will later be described.

Again 'referring to the bottom skid structure, it will be noted that the bottom skid 3 has extendingvalong the sides thereof at its forward portion, vertical retaining walls 63, 63 outwardly flared at their forward ends for directing, when the main frame 6 is in its rearward position on the skid 3, vthe broken-down coal moved rearwardly by the bottom kerf cutter 8, onto the receiving portion of the conveyor and for retaining the coal in the path of the receiving portion of the conveyor. When the main frame 6 is fed forwardly relative to the skid 3, the receiving portion of the conveyor of course moves forwardly from its position between the sides of these vertical retaining walls.

Now referring to the improved cutting and breaking-down means generally designated I, it will be noted that the bottom support 'I for the bottom kerf cutter 3 comprises a frame 65 mounted on and secured to the forward portion lof the sliding frame 6, as shown in Fig. 4. The forward portion of this frame has a circular bearing support 66 supporting a bearing sleeve on which a cylindrical portion 61 of a tiltable front frame 68 is mounted. It will thus be seen that ,theV front frame 68 vof the bottom support is tiltable about a horizontal axis extending longitudinally of the apparatus, and the means for tilting this front frame comprises a pair of vertical cylinders 69 (Fig. 4) supported by the frame 65 at the opposite sides of the tiltable front frame and containing plungers 76, the latter engaging at their lower lends lever-like projections 'Hintegral with the sides of the tiltable front frame. It will thus be seen that when fluid under pressure is supplied to one or the other of the cylinders 69 the pistons may be moved to tilt the front frame about its axis relative to the rear frame, and when fluid is trapped within'these cylinders the front frame is locked in its adjusted position. As shown in Fig. 3, the front frame 68 has adepending cylindric bearing support 'i2 supporting a bearing sleeve on which is swivelly mounted an annular bearing portion 13 of a pivoted arm 14. This arm has a circular flange 'i5 cooperating with an annular retaining ring 16 secured to the front frame 68. The arm 14 eX- tends forwardly in advance of the bottom support vll in the manner shown in Fig. 8, and has formed on its outer extremity cylindrical bearing supports Ti on which are supported bearing sleeves, the latter in turn having rotatably mounted thereon cylindrical annular bearing portions 13 and 79 formed integral with a hanger frame for the bottomkerf cutter 8. The kerf cutter 8 is in the form of an elongated plane cutter bar 8| supported by the hanger frame 80 and having guided for circulation about its margin an endless cutter chain 82. It will thus be seen that the kerf cutter may `be swung relative to the arm about an axis parallel to the arm pivot axis. The driving means for the cutter chain comprises a motor, herein preferably of the reversible electric type, having its power shaft 03 horizontally disposed and extending longitudinally of the apparatus. Keyed to the forward end of the motor power shaft is a bevel gear 84 meshing with a bevel gear 85, the latter in turn driving a spur gear 86 meshing with a large spur gear 81 having its hub connectible to a vertical shaft 88 suitably journaled within the tiltable front frame 68. The shaft 88 is arranged with its axis coincident with pivotal axis of the arm 74, and has keyed thereto at its lower end and drives a chain sprocket 89. This chain sprocket 99 is connected by an endless drive chain 90, arranged within the arm 14, to a sprocket 9| (see Fig. 8) keyed to a vertical shaft 92. The shaft 92 is suitably journaled within bearings supported within the arm 14 and is arranged with its axis coincident with the axis of pivotal movement of the lower kerf cutter. Keyed to the lower end of and driven by the shaft 92 is a chain sprocket 93 which engages and drives the endless cutter chain 82.

The structure of the upper support 9 is essentially the same as that of the lower support 'I and the top kerf cutter is similarly pivotally mounted and corresponding, parts are indicated by primed numbers. The top kerf cutter is, however, in this instance, pivotally mounted on the outer end of an arm 94 similar to the arm 14, and the cutter bar thereof is arranged above the arm instead of below the arm as is the cutter bar of the lower kerf cutter, and the arm 94 is preferably pivotally mounted on the top of the tiltable front frame. The top kerf cutter, in this instance, comprises an elongated plane cutter bar 95 having guided for circulation about its margin an endless cutter chain 9S, and this cutter chain moves about the margin of its cutter bar in a direction opposite from the direction of movement of the cutter chain 82 of the bottom kerf cutter, for a purpose to be later explained. The top and bottom arms are independently swingable about their pivots relative to the supports and the kerf cutters are independently swingable about their pivotal mountings on the outer ends of the arms relative to the arms, and the means for swinging the arms and kerf cutters about their respective pivotal axes will now be described. Each of the supports 'l and 9 has at the opposite sides thereof lateral projections 91, 91 in the form of split clamps in which are mounted hydraulic cylinders 98, 98. These cylinders are arranged in parallel relation and extend longitudinally of the support at the opposite sides thereof. Reciprocable in these cylinders are pistons 99 having piston rods |00 extending rearwardly through the packed rear heads of the cylinders and carrying at their rearward ends brackets |9| on which guide sheaves |02 are journaled. The arms '|4 and 94 have annular flanges |03 coaxial with the arm pivot and formed with an annular cable guiding groove |04. Secured to the arm at |05 are cables |06, |06 passing about the cable guiding groove |04 and extending rearwardly along the opposite sides of the support and around the guide sheaves |02, the opposite ends of these cables being fixed at |07 to the lateral projections 91. It will thus be seen that when fluid under pressure is supplied to one or the other of the cylinders 98 one of the pistons is moved rearwardly to deect one of the cables, thereby to swing the arm, together with the kerf cutter supported thereby, in one direction or the other about its pivot, and when fluid is trapped within the cylinders the arm is locked in its adjusted position. The means for swinging the kerf cutters 8 and 0 about their respective pivots relative to the arms each comprise a hydraulic cylinder |08 pivotally mounted at |09 about an axis parallel to the pivotal axis of the kerf cutter on a bracket integral with the arm and containing a reciprocable piston |0 having its piston rod extending forwardly through the packed front head of the cylinder and pivotally connected at 2 on a parallel axis to an arm ||3 integral with the cutter bar hanger frame. When fiuid under pressure is supplied to one end or the other of the cylinders |08 the kerf cutters may be swung about their respective pivots relative to the arms in one direction or the other, and when uid is trapped within these cylinders the kerf cutters may be locked in their adjusted position. From the foregoing, it will be evident that the supporting structure for the top kerf cutter I0 is identical to that for the bottom kerf cutter 8 with the exception that the upper supporting structure is in inverted relation.

To facilitate the breaking down of the coal cut by the kerf cutters, the bottom kerf cutter 8 has near its outer extremity a vetrically disposed rotary cutter ||4 comprising a rotary cutter bar I5 (see Figs. 9 and 10) projecting upwardly from the cutter bar 0| and having a lower shaft portion 6 keyed within the hub of a sprocket driven by the cutter chain 82. The rotary bar has attached thereto a series of cutters ||0. When the bottom kerf cutter 8 is sumped into the coal and then fed transversely to effect its transverse cutting operation, the vertical rotary cutter ||4 frees the coal at the inner end of the kerf cut by the bottom kerf cutter so that the top kerf cutter may be operated, as later explained to break down fragments of the cut coal with comparative ease as cutting progresses. If desired, a similar rotary cutter may be provided at the bottom of the outer portion of the top kerf cutter and similarly driven by the top cutter chain, for further. facilitating the breaking down of the coal. Mounted on the top of the lower cutter bar 8| near its rearward end is a transverse guide member ||9 (see Figs. 5, 6 and 7) providing a socket for receiving a projection |20 integral with a bracket |2|. Detachably secured to the outer edge of this bracket is a vertical plate |22 extending longitudinally in parallelism with the cutter bar, and this plate retains the coal in the path of the lower cutter chain 82 during the cutting and loading operation.

The plate |22 may be detached from the bracketv |2| the bracket reversed with respect to the cutter bar andthe plate reversed end for end with respect to the bracket and transposed to the opposite side of the bar and thereafter attached to the bracket so that the plate extends in parallelism with the bar at the opposite side thereof to retain the coal in the path of the cutter chain when the cutter is operating in the reverse direction.

The upper support 9 for the top kerf cutter I0 is, as aforementioned, adjustably mounted on tical guide members |46 secured to the opposite' the lower kerf cutter Support 1, and the adjustable supporting structure for the upper support comprises a plurality of hydraulic jacks, herein three in number, one at the front-end 'of the support and two at the rear end thereof and respectively designated |25, |26 and |21. The front jack |21 is arranged at the longitudinal vertical center of the adjustable support and comprises a vertical cylinder |28 (see Fig. 3) secured at its lower end within a bracket |29 pivotally mounted at |30 in a swiveled bracket |3I. The bracket |3| is swiveled at |32 on the tiltable front support 68 of the lower support 1, and the swivel axis of the bracket |3| is arranged coincident with the axis of tilting movement of the front support 68. The swivel brackets |29, |3| cooperate to form a universal pivotal mounting for the cylinder |28. Reciprocable'in this cylinder is a piston |33 having its piston rod |34 extending upwardly through the packed upper head of the cylinder, and the upper end of this piston rod is pivotally connected at |35 to a swiveled bracket |36. The bracket |36 is swiveled at |31 on the upper tiltable front frame 68', and the swivel axis of the bracket |36 is arranged in coincidence with the axis of tilting movement of the upper front frame 68'. The swivel axes of the piston rod and swivel bracket are so arranged as to provide a universal pivotal mounting for the upper end ofthe piston rod. The universal pivotal mountings for the opposite ends of the front jack |21 permit independent tilting movements of the front supports 66 and 68 while the jack supports the forward end of the upper support 9 on the forward end of the lower support, and these universal pivotal mountings also permit tilting movement of the upper kerf cutter support about a transverse axis relative to the lower kerf cutter support. Ihe rearwardly located jacks |25, |26 each comprise a vertical cylinder |39 rigidly secured to the rear end of the lower support 1 and containing a reciprocable piston |40 having its piston rod |4| extending upwardly through the upper packed head of the cylinder. The upper ends of the piston rods |4| are pivotally connected at |42 to projections |43 secured to the rear end of the upper support 9. It will thus be seen that when fluid under pressure is supplied concurrently to the frontl and rear jacks |25, |26 and |21 the upper kerf cutter support 9 may be moved either upwardly or downwardly in parallelism with respect to the lower 4 kerf cutter support, and when hydraulic pressure is supplied independently to the front and rear jacks the upper support` 9 may be tilted about a transverse axis either upwardly or downwardly relative to the lower support,lthereby to effect tilting of the top kerf cutter either upwardly or downwardly in the direction of its length. When iluid under pressure is supplied tothe tilting cylinders 69, 69', the front frames 68 and 68 may be tilted about their respective longitudinal axes to tilt the bottom and top kerf cutters laterally in an edgewise direction. It will thus be seen that the top and bottom kerf cutters may be independently tilted about longitudinal axes and the top kerf cutter may be tilted relative to the bottom kerf cutter about a transverse axis, for a purpose to be later explained. For guiding the upper kerf cutter support 9 during its vertical elevating and tilting movements with respect to the bottom kerf cutter support, there are provided a pair of verticalV hydraulic pump |48.

|49 arranged within the sliding main sides of the lower support 1, these guide members cooperating to hold the upper kerf cutter support against lateral displacement while permitting movement thereof Ain a vertical direction.

Now referring to the hydraulic fluid system and the associated control means, it will be noted that driven by the shaft-26 (see Fig. 14) 0f the transmission gearing between the motor 23 and the cable winding drum 38 is a shaft |41 of a This pump comprises a casing frame 6 and having a chamber containing intermeshing pump rotors |50. The main frame 6 is provided with a chamber |5| adapted to contain a liquid, preferably oil, and the pump intake communicates with this chamber. As shown in Fig. 15, the pump discharge is connected by a fluid pressure supply conduit |52 with a pressure supply passage |53 of a horizontal valve box |54.

The valve box has formed therein a series'of horizontal bores containing slide valves of the balanced spool type. Extending longitudinally'of the valve box and communicating with the sup- Yply passage |53 is a pressure passage |55, the

"latter passage communicating with the valve bores centrally between their ends as shown in Fig. 16. Communicating with the ends o-f the valve-ceceiving bores are discharge passages |56, |56, in turn communicating with a discharge passage |51 connected by a discharge conduity |58 back of the cylinder.

to the liquid containing chamber |5|. The slide valves are respectively designated |59, |60, |6l,

-6|] and through a conduit |14 to the lower ends of the jack cylinders. These conduits are provided with manual control valves |15 and |16 respectively whereby the fluid supply to the jack cylinders may be independently controlled.' The valve |60 controls the supply of fluid under pressure to `the front jack 54 and has its receiving bore connected by a conduit |11 to the upper end of the jack cylinder 51 and through a conduit |18 to the lowerend of the jack cylinder.

- The valve |6| controls the supply of fluid under pressure to the feed cylinders 46 and has its lreceiving bore connected through a conduit |19 to the rear ends of the feed cylinders and through a conduit to ther forward ends of the feed cylinders. The valve |62 controls the supply of fluid under pressure to the rear elevating cylinders |39 of the rear jacks |25 and |26 and has i its receiving bore connected through conduits |8| and |82 to the opposite ends Aof the cylinders.

",The valve |63 controls the ilow of fluid under pressure to the elevating cylinder |28 of the front jack |21 and its receiving bore is connected through conduits |83 and |84 to the opposite ends The valve |64 controls the flow Yof fluid under pressure to the tilting cylinders 69 for the bottom kerf cutter and has its receiving bore connected through conduits and |86 to the upper ends of the cylinders. The Valve |65 controlsthe supply of fluid under pressure tothe .tilting cylinders 69' for the top kerf cutter and has it-s receiving bore connected through conduits |81 and |88 to the lower ends of the cylinders. The valve |66 controls the supply of fluid under pressure to the swinging cylinders 98 for the bottom kerf cutter supporting arm 14 and has its receiving bore connected through conduits |90 and |9| to the forward ends of the cylinders. The valve |61 controls the supply of iuid under pressure to the swinging cylinders 98 for the top kerf cutter supporting arm 94 and has its receiving bore connected through conduits |92 and |93 to the forward ends of the cylinders. The valve |68 controls the supply of iiuid under pressure to the cylinder |08 for swinging the vbottom kerf cutter about its pivot and has its receiving bore connected through conduits |04 and |95 to the opposite ends of the cylinder. The valve |88 controls the supply of iiuid under pressure to the Cylinder |08 for swinging the top kerf cutter about its pivot and has its receiving bore connected through conduits |96 rand |91 to the opposite ends of the cylinder. As shown in Fig. 18, the conduit |11 leading to the top of the front jack cylinder l is connectible through an automatic by-pass valve |98 to one of the discharge passages 56, so that when the pressure of the iuid at the upper side of the front jack piston becomes excessive, the by-pass valve will open automatically to reduce the pressure. By shifting the valves back and forth axially within their receiving bores in the valve box the conduits leading to the various cylinders may be connected either to the supply or discharge.

In Figs. 19, and 21 there is shown a cutting and loading apparatus similar to that described above, having a modified form of supporting structure for the kerf cutters. In this embodiment of the invention, the feeding and walking jack structure for the sliding main frame, the conveying means, the upper and lower supports for the kerf cutters and the adjustable supporting structure for the upper support, are the same as those described above, and like parts are designated by like reference characters. In this instance, however, the independently swingable supporting arms 74 and 84 for the kerf cutters are omitted and the kerf cutters are pivotally mounted directly on the tiltable front frames 68 and |50A of the lower and upper supports and 9. The upper and lower kerf cutters are designated 205 and 208 respectively, and each comprises an elongated plane cutter bar 201 having guided for circulation about its margin an endless cutter chain 20B. The lower kerf cutter 206 is mounted on a hangar frame 209 having a bearing support corresponding to the bearing support 13 for the lower arm lll, while the upper kerf cutter is mounted on a similar hanger frame 2|0 on the top of the tiltable front support 68', and these hanger frames are swiveled (see Fig. 2l) on the cylindric bearing supports 12 and 'I2' of the tilting front supports in the same manner as the arms 'M and 94 shown in Fig. 3. The cutter chains 208 of the upper and lower kerf cutters are driven in relatively opposite directions by the motors on the supports 1 and 0 through similar transmission gearing, except in this construction the. chain sprockets 88 and 89 directly engage and drive the cutter chains, instead of the transmission chains 90 and 90' shown in Fig. 3. In this construction, the bar-swinging cylinders |08 are omitted and the cutter bars are swung about their pivots by swinging means similar to the swinging means for the arms 14 and 94 of the form of the invention above described and shown irespective pivotal axes.

in Fig. 5. vOtherwise this form of the invention is the same as that above described.

The general mode of operation of the improved mining apparatus is as follows: The ap- 5 paratus may be moved bodily over the mine iloor duringimaneuvering of the apparatus with respect to the coal face at a relatively high moving speed by the feed drum 38 and its cooperating feed cable 45. When this apparatus `is in its cutlfg; ting and .loading position` at the coal face, as

shown in Fig. 22, fluid under pressure may be supplied to certain .of the swinging cylinders 98 for the lower and upperarms .14 and 94, thereby swinging the :kerf cutters simultaneously about 115i the arm pivot axes `into the dotted line position indicated at A. By independently swinging the upper .and lower cutter-supporting arms, the bottom kei-.f .cutter may be located with its eiective cutting portion in advance of the top kerf cutter di so that the bottom kerf cutter cuts a kerf in the coal `in advancer of the top kerf cutter inthe manner .shown in Fig. and the desired angular relation of the kerf cutters relative to the arms may be obtained by the kerf-cutter-swinging cyl- 25g-inders |08. When the kerf cutters are in the 35Llmain frame S is slid `forwardly along its guideways relative to the bottom skid plate 3, thereby sumping the kerf cutters into the coal from the position indicated at A to the dotted line position indicated .at Bin Fig. `22. When the sumping cut is completed, uid under pressure vis supplied to certain of the arm swinging cylinders 98, 98 and the kerf cutters are swung simultaneously about the arm pivot axesacross the coal face to form superimposed, parallel, arcuate cuts in the coal.

The mid-positionof the kerf cutters during their swinging movement across the coal face is indicated in full lines'at C in Fig. 22 and the position of the kerf cutters at the completion of the swinging cut across the coall face is indicated in 56 fdotted linesat D in Fig. 22. When the swinging cut is completedthe tip ends of the kerf cutters are located near the right hand rib, and the uid is trapped within the arm `and kerf-cutterswinging cylinders 08,` 93 and |08, 08 to lock the arms and` kerf cutters against swinging movement about their respective pivotal axes, Fluid under pressure Vis then supplied to the feeding cylinders 46,'and the sliding main frame 6 is slid rearwardly along its guideways relative to the 6d bottom skid plate 3, moving the kerf cutters from the position indicated -at D in Fig. 22 to the dotted line position indicated `at E in that gure, thereby withdrawing the kerf cutters from the coal. As the kerf cutters are sumped in, swung `2transversely across the coal face and withdrawn from the coal, parallel superimposed kerfs are cut in the coal, thereby forming a core of coal between thekerfs, and as the kerf cutters are moved relative to the coal the elevating jacks 765325, |26 and .|21 maybe so operated to tilt the top kerf cutter |0 about a transverse axis in the direction of its length as shown in Fig. 24, thereby to apply a breaking down pressure to the top of the core of coal, and as a result, as cutting progresses, fragments of the core are broken down. Also during the cutting operation iiuid under pressure may be supplied to the tilting cylinders 69, 69' for the tiltable front frames 68 and 68' of the lower and upper supports 'l and 9, thereby to tilt the kerf cutters about longitudinal axes in an edgewise direction to permit the kerf cutters to follow a rolling bottom or pitching coal seam, and this tilting movement of the top kerf cutter also aids in the breaking-down of the core of coal. The top kerf cutter may be adjusted upwardly and downwardly into dierent parallel cutting positions relative to the bottom kerf cutter by simultaneously operating the elevating jacks I25, 125 and |21, thereby enabling the apparatus to cut in coal seams of varying height and to cut cores of diierent thickness. The retaining plate |22 attached to the trailing edge of the bottom kerf cutter retains the brokendown coal in the path of the bottom cutter chain so that the cutter chain gathers the broken-down coal from the mine floor and moves it rearwardly toward the receiving portion of the conveyor. As the broken-down coal is received by the conveyor, it is moved rearwardly from the mine floor along .the conveyor trough at one side of the main frame to discharge in an elevated position at the rear end of the apparatus. The conveyor may discharge the coal into a suitable receptacle such as a mine car or onto a conveyor mechanism in a well known manner. When the sumping, swinging and withdrawal cuts are completed and the core of coal has been completely broken down from the coal face and the broken-down coal has been conveyed away from the coal face, the walking jacks 54, 55 and 56 are operated to raise the main frame 6 from the skid 3 to relieve the latter substantially of the weight of the appartus, and the feed cylinders 46 are then operated to move Vthe skid forwardly beneath the main frame, and thereafter the jacks are operated to lower the main frame again onto the skid. The feed cylinders 46 are then again operated to move main frame forwardly relative to the skid to sump the kerf cutters into the coal, and the sumping, swinging and withdrawal operations above described are repeated. The vertical rotary cutter H4 mounted on vthe bottom kerf cutter moves with the latter during the sumping, swinging and withdrawal cutting operations, and this rotary cutter acts to free the core of coal at theA inner end of the kerf cut by the bottom kerf cutter so that the top kerf cutter may be operated to-break down fragments of the core with comparative ease as cutting progresses. When the -cutter driving motors are reversed, the cutter bits reversed in their respective links in the cutter chains, the bottom kerf cutter swung in the opposite direction in advance of the top kerf cutter, Vand the retaining plate transposed to the opposite side of the bottom cutter bar, the apparatus may cut and load in the opposite direcl tion, i. e. from right to left.

the `bottom kerf cutter may be swung about its pivot forwardlya slight distance in advance of the, top. kerf cutter, so that the bottom kerf cuttercuts a. kerf inadvanceof the kerf cut by the top ikerfcutter.

that an improved coal mining apparatus is provided for completely removing the solid coal from its natural bed in a coal seam, wholly without the use of explosives or other blasting means, and for loading the coal as it is removed fro-m the coal seam. It will further be noted that an improved coal mining apparatus of the combined cutting and loading type is provided having improved means for cutting and breaking down the coal, and an improved adjustable supporting structure for the cutters whereby the apparatus is rendered extremely iiexible in operation and has a relatively wide cutting and loading range. It will still further be evident that by the novel arrangements and combinations of parts the apparatus is not only relatively flexible in operation but is also extremely compact and rugged in design, well adapted to meet the severe conditions of service in the mining of coal. Other advantagesv and uses of the improved coal cutting and loading `apparatus will be clearly apparent to those skilled in the art.

While there are in this application specically described one form and a modication which the invention may assume in practice, it will be understood that thisform and modification of the same are shown for purposes of illustration and that the invention may be further modied and embodied in various other forms without departing from its spiritor the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a mining and loading apparatus, in combination, a portable base, conveying means on said base having its receiving end disposed near the level of the mine floor at the forward end of said base, and core cutting and breaking down mechanism on said base comprising parallel horizontal top and bottom kerf cutters having orbitally moving cutting elements, the bottom kerf cutter being disposed near the oor level in advance of the receiving end of said conveying means and the top kerf cutter being disposed a substantial distance above the floor level, means for mounting said kerf cutters on said base in the positions aforesaid with the active cutting portion of one kerf cutter disposed in advance of the active cutting portion of the other kerf cutter, said mounting means including means for pivotally supporting said kerf cutters for hori- Zontal swinging movement relative to said base and conveying means, said mounting means also including means for adjustably supporting the top kerf cutter for adjustment in a vertical direction relative to the bottom kerf cutter, means for horizontally swinging said kerf cutters simultaneously about their pivotal mountings relative to said base and conveying means for cutting simultaneously a pair of parallel horizontal kerfs in a coal seam to form a core of coal between the kerfs, and means for adjusting the top cutter in a vertical direction relative to the bottom kerf cutter to apply, at a point spaced horizontally from the bottom kerf cutter, a breaking down pressure to the core of coal to break down fragments of the core as cutting progresses, the .bottom kerf cutter being so arranged with respect to the receiving end of said conveying means that said orbitally moving cutting elements thereof move the broken down coal over the mine floor toward the receiving end of said conveying means.

2. In a miningl and loading apparatus, in comf vAs a result of this invention, it will be notedY bination, a portable base, conveying means on said base having its receiving end disposed near the level of the mine floor at the forward end of said base, and core cutting and breaking down mechanism on said base comprising parallel horizontal top and bottom kerf cutters having orbitally moving cutting elements, the bottomkerf cutter being disposed near the floor level in advance of the receiving end of said conveying means and the top kerf cutter being disposed a substantial distance above the iloor level, means for mounting said kerf cutters on said base in the positions aforesaid with the active cutting portion of the bottom kerf cutter disposed in advance of the active cutting portion of the top kerf cutter and including means for pivotally supporting said kerf cutters for horizontal swinging movement relative to said base and conveying means, said mounting means also including means for adjustably supporting the top kerf Y cutter for adjustment in a vertical direction relative to the bottom kerf cutter, means for horizontally swinging said kerf cutters simultaneously about their pivotal mountings relative to said base and conveying means for cutting simultaneously a pair of parallel horizontal kerfs in a coal seam to form a core of coal between the kerfs, and means for adjusting the top kerf cutter in a vertical -direction relative to the bottom kerf cutter to apply, at a point spaced horizontally rearwardly of the bottom kerf cutter, a breaking down pressure to the core of coal to break down fragments of the core as cutting progresses, the bottom kerf cutter `being so arranged with respect to the receiving end of said conveying means that said orbitally moving cutting elements thereof move the broken down coal over the mine floor toward the receiving end of said conveying means.

3 In a mining and loading apparatus, in combination, a portable base, conveying means on said base having its receiving end disposed near the level of the mine floor, core cutting and breaking down mechanism on said base comprising parallel horizontal 'top and bottom kerf cutters having orbitally moving cutting elements, the bottom kerf cutter being disposed near the iloor level in advance of the receiving end of said conveying means and the top kerf cutter disposed a substantial distance above the door level, means for mounting said kerf cutters on said base in the positions aforesaid with the active cutting portion of one kerf cutter disposed in advance of the active cutting portion of the other kerf cutter, said mounting means including means for pivotally supporting said kerf cutters for horizontal swinging movement relative to said base and conveyingmeans, said mounting means also including means for adjustably supporting the top kerf cutter for adjustment in a vertical direction relative to the bottom kerf cutter, means for horizontally swinging said kerf cutters simultaneously about their pivotal mountings relative to said base and conveying means for cutting simutaneously a pair of parallel horizontal kerfs ina coal seam to form a core of coal between the kerfs, means for adjusting the top cutter in a vertical direction relative to the bottom kerf cutter to apply, at a point spaced horizontally from the bottom kerf cutter, a breaking down pressure to the core of coal to break down fragments of the core as cutting progresses, the bottom kerf cutter being so arranged with respect to the receiving end of said conveying means that said orbitally moving cutting elements thereof move the broken down coal over the mine floor toward the receiv- Htl lbination, a portable base, and core cutting and breaking down mechanism on said base comprising a pair of parallel horizontal kerf cutters, means for pivotally mounting said kerf cutters on saidbase for horizontal swinging movement relative to said base comprising arms pivotally mounted for horizontal swinging movement on said base, means for pivotally mounting said kerf cutters on said arms respectively, to swing horizontally relative thereto about pivotal axes paral- 4lel to the arm pivot axes, means for independently adjusting said kerf cutters horizontally about their pivotal axes on said arms into dilerent angularly related positions relative to said arms so that the active cutting portion of one kerf cutter is disposed in advance of the active cutting portion of the other kerf cutter, and means for swinging said arms simultaneously about their pivotal axes, when said cutters are in angularly adjusted position relative to said arms, to swing said kerf cutters simultaneously bodily in arcuate paths about the arm pivot axes to cut parallel horizontal kerfs in a coal seam to form a core of coal between the kerfs.

5. In a mining and loading apparatus, in comlbination, a portable base, and core cutting and breaking dov/n mechanism on said base comprisying a pair of parallel horizontal kerf cutters,

means for pivotally mounting said kerf cutters on said base for horizontal swinging movement relative to said base comprising arms pivotally mounted for horizontal swinging movement on said base, means for pivotally mounting said kerf cutters on said arms respectively, to swing horizontally relative thereto about pivotal axes parallel to the arm pivot axes, said mounting means for the top kerf cutter embodying means including a further pivotal mounting whereby the top kerf Vcutter may be tilted in a vertical direction relative to the bottom kerf cutter, means for independently adjusting said kerf cutters horizontally about their pivotal axes on said arms into different angularly related positions relative to said arms so that the active cutting portion of one kerf cutter is disposed in advance of the active cutting portion of the other kerf cutter,

) means for swinging said arms simultaneously about their pivotal axes, when said cutters are in angularly adjusted position relative to said arms, to swing said kerf cutters simultaneously bodily in arcuate paths about the arm pivot axes to cut parallel horizontal kerfs in a coal seam to form a core of coal between the kerfs, and means for tilting the top kerf cutter about its said further pivotal mounting in a vertical direction relative tothe bottom kerf cutter to apply a breaking'down pressure to the core of coal to break down fragments of the core as cutting progresses.

`6. In a mining and loading apparatus, in combination, a portable base, core cutting and breaking down mechanism on said base comprising a pair of parallel horizontal top and bottom kerf cutters, the bottom kerf cutter disposed near the level of the mine door in advance of the forward end of said base andthe top kerf cutter disposed a substantial distance above the floor level, means for pivotally mounting said kerf cutters on said for pivotally mounting said kerf cutters on saidl arms respectively, to swing horizontally relative thereto about pivotal axes parallel to the arm pivot axes, said mounting means for the top kerf cutter embodying means including a further pivotal mounting whereby the top kerf cutter may be tilted in a vertical direction relative to the bottom kerf cutter, means for independently adjusting said kerf cutters horizontally about their pivotal axes on said arms into different angularly related positions relative to said arms so that the active cutting portion of one kerf cutter is disposed in advance of the active cutting portion of the other kerf cutter, means for swinging said arms simultaneously about their pivotal axes, when said cutters are in angularly adjusted position relative to said arms, to swing said kerf cutters simultaneously bodily in arcuate paths about the arm pivot axes to out parallel horizontal kerfs in a coal seam to form a core of coal between the kerfs, means for tilting the top kerf cutter about its said further pivotal mounting in a vertical direction relative to the bottom kerf cutter to apply a breaking down pressure to the core of coal to break down fragments of the core as cutting progresses, and conveying means on said base for receiving the broken down coal and moving the same 1' away from thel coal face, the bottom kerf cutter moving the broken down coal away from the coal face over the .mine floor toward the'conveying means. :i

7. In a mining and loading apparatus, in combination, a portable base, and cutting and breaking down mechanism on said base comprising a pair of parallel horizontal top and bottom kerf cutters, means for mounting said kerf cutters on said'base for independent horizontal swinging movement relative thereto about verticalv axes,

vsaid mounting means including upper and lower supports on which said kerf cutters are respectively pivotally mounted and means for adjustably supporting the support for the `top kerf cutter for tilting movement about transverse and longitudinal axes relative to the support for the bottom kerf cutter, means for horizontally7 swinging said kerf cutters simultaneously about their pivotal mountings relative to said supports, and means for tilting the ,support for the top kerf cutter about said transverse and longitudinal axes relative to said lower support to tilt the top kerf cutter relative to the bottom kerf cutter.

8. In a mining and loading apparatus, incombination, a portable base, and cutting and breaking down mechanism on said base comprising a pair of parallel horizontal top and bottom kerf cutters, means for mounting said kerf cutters on said base including means for pivotally supporting said kerf cutters `for independent horizontal swinging movement relative to said base about vertical axes, said mounting means including upper and lower supports on which said kerf cutters are respectively pivotally mounted and means for adjustably supporting said supports for tilting movement about longitudinal axes relative to said base, means for Ahorizontally swinging said kerf cutters simultaneously about their pivotal mountings relative to said supports, and means fortlting said supports about said longitudinal axes respectively to tilt said kerf cutters about longitudinal axes relative to said base. n

9. In a mining and loading apparatus, inn combination, a portable base; and cutting andgbreak-` ing down mechanism on saidbase comprising a pair of parallel horizontal top and bottom kerf cutters, means for mounting said kerf cutters on said base including means for pivotally supporting said kerf cutters for independent horizontal swinging movement relative to said r,base about vertical axes, said supporting means including upper and lower supports on which said kerf cutters are respectively pivotally mounted and means for adjustably mounting said supports for tilting movement about longitudinal axes relative to said base, said .mounting means also including means for adjustably supporting said Yupper support for tilting movement -about a transverse axis relative to said lower support, means for horizontally swinging said kerf cutters simultaneously about their pivotal mountings relative to said supports, means for tilting said supports about said longitudinal axes relativey to said base respectively to tilt said kerf cutters about longitudinal axes, and means fortiltinf,r said upper support about said transverse axis relative to the lower support to tilt the top kerf cutter in a vertical direction relative to the bottom kerf cutter. Y Y e 10. In a mining and loading apparatus-in combination, a portable base, conveying means on said base having its receiving end disposed near the level of the mine floor at the forward end of said base, and core cutting and breaking down mechanism supported on said base comprising parallel horizontal top and bottom kerf cutters having orbitally moving cutting elements, the bottom kerf Acutter being disposed at the floor level in advance of the receiving end of said conveying means and the top kerf cutter being disposed a substantial distance above the floor level, means for. mounting saidjkerf cutters on the forward portion of said base in the positions aforesaid including means for pivotally supporting said kerf cutters for independent swinging movement horizontally relative to said base, said pivotal mounting means including arms' pivotally mounted to swing horizontally relative to said base and on which said kerf cutters are respectively mounted, said mounting means including means for independently adjusting the angular relation of said kerf cutters relative to said arms respectively and means for adjustably supporting the top kerf cutter for adjustment in a vertical direction relative to the' bottom kerf cutter, means for swinging said arms simultaneously about their pivotal mountings to swing said kerf cutters simultaneously bodily in arcuate paths simultaneously a pair of parallel horizontal kerfs in a coal seam to form a core of coal between the kerfs, and means for adjusting the top kerf cutter in a vertical direction relative to the bottom kerf cutter to apply a breaking down pressure to the core of coal to break down fragments of the core as cutting progresses, the cutting ele.. mentsr of the bottom kerf cutter being so arranged with respect to the receiving end of said conveying means that the orbitally moving cutting elements thereof move the broken down coal over the mine floor toward the receiving end of said conveying means. v

l1 In a mining and loading apparatus, in combination, a portable base, conveying means on said base having its receiving end disposed near the level of the mine floor at the forward Y end of said base, core cutting and breaking down 

